Risk Factors and Risk Assessment

The importance of hospitalisation

Venous thromboembolism (VTE), encompassing DVT and PE, is a common disease, with an average annual incidence rate of about one case per 1000 [3]. A large, population-based study has shown that about half of all VTE episodes are provoked by hospitalisation for either surgery or a medical illness [3]. Of note, hospitalisation for either surgery or a medical illness accounted for similar proportions, emphasising the need to consider the risk of VTE in all hospitalised patients.

In this population study, other recognised risk factors accounted for 25% of all cases of VTE, and the remaining 25% of cases were not explained by accepted VTE risk factors and were regarded as idiopathic. This study pointed to the importance of identifying risk factors for VTE, in particular in people currently or recently hospitalised [3].

Preventing hospital-associated thrombosis (HAT)

Preventing VTE associated with hospitalisation (known as hospital-associated thrombosis, or ‘HAT’) is widely accepted as a key patient safety priority and within the UK a comprehensive VTE Prevention Program has been in place since 2010 that includes a national VTE risk assessment tool coupled with mandatory reporting of risk assessment rates [25].

Achieving high rates of VTE risk assessment was financially incentivised through the CQUIN (Commissioning for Quality and Innovation) payments framework and this has resulted in very high risk assessment rates that have reduced the incidence of HAT [25]. In addition, it has been shown that this national quality initiative to increase the number of hospitalised patients assessed for risk of VTE has resulted in a reduction in VTE mortality [26].

An individual’s risk profile determines the need for VTE prophylaxis

National Institute of Health and Care Excellence (NICE) clinical guidelines on reducing the risk of VTE linked to NICE Quality Standards provide simple care pathways to direct VTE risk assessment and support prophylaxis decision-making. These guidelines offer advice on how to decide the type and duration of prophylaxis. Given the increased risk of bleeding associated with anticoagulant use for prophylaxis, individualised patient assessment of VTE and bleeding risks is advocated.

A person’s risk of VTE is determined on a case-by-case basis, taking into account the existing relevant risk factors of VTE and the chance that thromboprophylaxis may cause a side effect such as bleeding. Therefore, where relevant risk factors are present, an individually adjusted and risk-adapted thromboembolism prophylaxis is generally recommended [27].

In the case of surgically and medically ill patients, the individual overall risk of VTE is identified on the basis of patient-related factors (e.g. cancer) and admission-related factors (e.g. surgery). The type and duration of prophylaxis is then determined on the basis of the risk stratification.